Endless v-type belt



- INVENTOR. Chews M/ EZM WTra/wvs C W YELM ENDLESS V-TYPE BELT Filed July 13, 1940 Feb. 24, 1942.

Patented Feb. 24, 1942 tween the inner ends of -Be1ts df the time under consideration are used the side walls of that the sticking UNl TED STATES PATENT] OFFICE ENDLESS V-TYPE BELT Charles W. ,Yelm, Dena, 0010., assignor to The Gates Rubber Company, Denver, 0010., a corporation of Colorado Application July 13, 1940, Serial No. 345,290

3 Claims.

This invention relates to improvements in end- 1653 V-type belts. The use of V-type belts is very common in connection with power driven machinery of all kinds. Such belts are made in Various widths and thicknesses and are usually constructed from a body of rubber composition whose outer surface is enclosed in one or more resist tensional strains.

When V-type belts are applied to pulleys where the curvature is greater than the curvature of the mould in which they were cured, the belt will be curved on a smaller radius than that of the curing mould, which produces compressive strains in that portion of the belt between the layer of cord and the inner surface thereof. Since the belt is .constructed principally from rubber composition, the transverse cross sectional shape of the belt will change when such compressive strains occur and one of the changes resulting from this is -to widen the distance bethe inclined sidewalls.

in connection with pulleys having Viggshaped grooves of the proper angular inclination to obtain the best tractive effort with the belts employed. Due to the compression of the material in passing around the pulley, the

the pulley with greater force along its inner corners than along the outer corners thereof with the result that when the belt belt engages of wear and to some extent at least, decreasing the noise produced while running.

It has been found that the deformation 'of the transverse section of the belt takes place mainly at the inner corners thereof and it has also been found that withthe ordinary belts having sharp inner corners, the sticking effect is particularly noticeable and destructive to the belt.

Experiments have shown that if a belt of the type here under consideration, is so cohstructed that the inclined side walls are joined to the inner transverse wall of curved surface whose rate of curvature increases progressively from the inner edge of the side wall to where it merges with then the sticking action above pointed out will be greatly decreased and as a result thereof, the life of the belt correspondingly lengthened.

It has also-been found that such belts will operate with the production of less noise than the ordinary belt in which the side walls connect with the inner wall along a sharp corner.

In order to more clearly describe this invention, reference will be had to the accompanying drawing inwhich the preferred 'cross sectional shape of the belt has been illustrated, and in which:

- Figure 1 is a transverse section of a belt constructed in accordance with this invention, a portion of the cross section having been removed from one corner so as to permit the construction to be better illustrated;

Figure 2 is a fragmentary section similar to that shown in Figure tially twice the scale; and

Figure 3 is a cross section of a belt having straight inner and outer walls.

The line represented by reference numeral 5 in Figure 2 indicates the friction surface of a begins to leave the pulley after having been in contact therewith through its entire arc of contact, this outward movement will be resisted by the pressure which is produced by the transverse expansion of the belt, due to its increased curvature. This sticking of the belt to the walls of the pulley produces an unnecessary wear and as a result thereof, the covering of the belt usually wears away at th inner edges of the inclined walls before it wears away at any other place. 'of the belt also produces a noise The sticking while running, which indicates'unnecessary frictional resistance and loss of power. I v

It is the object of this invention to produce a V-type belt having such cross sectional shape referred to above will 'be greatly decreased, thereby decreasing the amount V-shaped pulley-and reference numeral 6 designates the bottom of the V.-shaped groove. The belt has been shown as of the usual construction and comprises a body I constructed principally of rubber compound which has been cured to produce an elastic resilient material. The inner surface of thebelt has been designated by reference numeral 8 as straight, whereas the outer surface has been 9 and. has been illustrated as outwardly convex. The inclinedsides have been designated by reference numeral l0 and have been shown convnected to the outer surface by means of a curved surface H, whose curvature ispreferably the same as that of the inner corners l2, which will now be described.

The side walls It) may be perfectly straight the belt by means of a the inner transverse wall,

'1, but drawn to substandesignated by reference numeral or somewhat concave from their upper edges to the point indicated by reference numeral l3. A line It is drawn perpendicular to the side wall at point l3 and reference numeral l5 desigoutside wall 9 is transversely straight and in which the layer of cords is also straight.

In the above description and in the drawing, the curvature has been shown as consisting of nates a center which is the center of curvature 5 several arcuate segments of different curvature of that section of the curve between points 13 and IS. The center of curvature of that part of curve l2 between points l6 and I1 is located on line Iii-I5 and has been designated by reference numeral I8. That part of the curve between points I! and 19 has its center of curvature on line |'Il8 at the point designated by reference numeral '20 while that part of the curve between points I 9 and 2| is located on line l9-20 at the point designated by reference numeral 22.

It will be seen from the above that the corners l2 are formed by curved surfaces whose rate of curvature increase progressively from point Hi to point 2| or, in other words, these surfaces-are formed from a plurality of adjacent annular zones whose radii of curvature decrease progressively from point I 3 to point 2|.

In Figure 2-the full lines designate the normal shape of the belt before it begins to curve about the pulley and the dotted line 23 indicates the outline of the corners l2, and the inner surface 8 after the belt has been curved to conform to'the pulley.

It will be observed from Figure 2 that the shape of the belt changes as a result of the compressive strains and that the transverse expansion is comparatively small between points l3 and I6, and since the curvature of that portion is comparatively small, that part of the corner surface will be -moved into contact with; the side 5 of the pulley, whereas the outer surface-between points l6 and I! may not come in contact with the friction surface of the pulley.

After the belt has passed around the pulley to the point where the arc of contact terminates, it will straighten quite suddenly, but instead of sticking to thesides of the pulley in the manner of the ordinary belt of this type, the part -of thercurved corner l2 between points -l3 and i6 will movesinwardly, thereby removing the pressure and'permitting the belt to release freely from the pulley. I The shape of the belt which permits the operation above described-also results in the elimination of that part of the noise which is due to the forceful separation of the belt from the pulley, that is always present in belts of the usual shape.

Another result of this particular shape is that the belt can flex more readily due to the-production of less compressive strains as a result of the added freedom and this greatly reduces band fatigue which in of the belt. k

Although the invention has been described in connection with Figures 1 and 2 which show a face, this is not essential. In Figure 3 a cross section ofa belthas been shownin which the turn serves to increasethe life appended claims.

In the embodiment illustrated, point l3 where I the curve commences, has been shown as positioned nearer the base than the top of the belt. It is to be understood that the point at which the curve commences can be raised or lowered as may be found 'most suitable without departing from the invention and the specific shape of the belt can be varied within the scope of the Having described the invention what is 'claimed as new is:

1. An endless rubber composition belt of the 'V-type, of greater width than thickness, having a transversely straight inside wall and an endless core of substantially inextensible cords embedded therein, the material between the cord core and the inside wall being resilient and elastic whereby its shape will change in response to variations in belt flexure, in which the inclined side wall surfaces are joined to the inside wall -of the belt by curved surfaces whose curvature increases progressively from the inclined side walls to theinside wall.

2. An endless rubber composition belt, of the V-type, of greater width than thickness, having a transversely straight inside wall and an endless core of substantially inextensible cords embedded therein the material between the cord core and the inside and the outside walls being resilient and elastic whereby that portion positioned between the cord core and the inside wall belt having a transversely convex outside surwill be compressed and change its shape in response to belt flexure, in which the inclined side wall surfaces are joineditothe inside and the outside wall surfaces by curved surfaces whose curvature increases progressively from the inclined side walls.

3. A rubber composition belt of the V-type having an endless core of substantially inextensible cords embedded therein, the material between the cord core and the inside wall being resilient and. elastic whereby its shape will change in response to distorting forces developed when the belt is flexed, in which the inclined wall surfaces of the belt are joined to the inside wall thereof by curved surfaces, whose curvature increases progressively from the inclined side walls to the inside wall.

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